The present invention relates to the art of projector trapezoidal correction.
There has been a recent dissemination of projectors arranged to project a video onto a screen. Such a projector is usually designed to basically face straight toward the screen. Where the projector is arranged so as not to face straight toward the screen, distortion is induced in the image.
When the projector is arranged not to face straight toward the screen, variation is encountered, not only in the image but also in its brightness distribution. Furthermore, where the projector is provided with an imager, the distance of imaging is not equal between the left of the screen versus the right of the screen. Due to the inverse-square law, the imager is to receive light in an amount different at the left and right of the screen. Such reception-light difference can be applied in estimating the screen inclination relative to the optical axis of the projector.
However, the reception light is varied not only by a screen inclination but also by such factors as individual differences or aging, in the projector projection system and imager optical system.
JP-A-2000-241874 is an example of a related art.